The present invention relates to built-in antennas.
In recent years, communication devices such as mobile terminal devices have steadily spread, and there has been a demand for miniaturization of communication devices. There has also been a demand for miniaturization and thin-modeling of built-in antenna devices that are built in these communication devices.
These built-in antenna devices should be able to operate at a wide bandwidth, within the bandwidth that is required by the mobile communication systems in which communications terminals such as mobile terminal devices are used.
Japanese laid-open patent publication No. 2000-349526 discloses an example of built-in antenna device of the above type. This built-in antenna aims to broaden bandwidth and, at the same time, aims at miniaturization and thin-modeling, by configuring an elongated antenna element into a continuous surface of a zigzag shape and such, without excessively shortening the length of its central axis length (antenna length), or by providing electro-magnetic wave absorbing material of a certain width near the antenna element.
Nevertheless, with a typical built-in antenna device, an antenna element has a continuous surface, or, a built-in antenna itself has a flat shape to have electro-magnetic wave absorbing material of a certain width provided, and thus a certain width is required and miniaturization and thin-modeling are limited.
Furthermore, an antenna needs to operate at a wide bandwidth and enhance gain during communication to utilize the frequency band used by a system, and yet a single antenna element can enhance gain only to a limited extent.
The present invention is therefore directed to broadening bandwidth, and realizing further miniaturization and thin modeling without making the whole device in a flat shape.
In addition to the miniaturization and thin modeling that does not require making the whole device a flat shape, the present invention is directed to enhancing gain and reducing SAR (Specific Absorption Rate).
The essence of the present invention is to broaden bandwidth and to make a built-in antenna device small and thin, by positioning a power-supplied radiation element and a parasitic element for use in matching in opposition to each other, and without making the radiation element a flat shape such as a thick board shape.
One aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in a same direction; a parasitic element for use in matching provided opposite to the radiation element, both ends of said parasitic element bent to the same direction as the both ends of the radiation element; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in a same direction; a parasitic element for use in matching provided opposite to the radiation element, one end of said parasitic element bent to the same direction as the both ends of the radiation element, and the other end bent to an opposite direction; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Yet another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in a same direction; a parasitic element for use in matching provided opposite to the radiation element, only one end of the parasitic element bent to the same direction as the both ends of the radiation element; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Yet another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in a same direction; a parasitic element for use in matching provided opposite to the radiation element, one end of the parasitic element bent to the same direction as the both ends of the radiation element, and the other end bent to a direction that is perpendicular to a plane of the circuit board; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Yet another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in a same direction; a parasitic element for use in matching provided near the radiation element on the circuit board; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Yet another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the element turned in a same direction; a case, at least a portion of which that is opposite to the radiation element over the circuit board is made of steel; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.
Yet another aspect of the invention presented herein is a built-in antenna device comprising: a radiation element of a dipole configuration that is supplied power and provided on a circuit board, both ends of the radiation element turned in mutually opposite directions; a case, at least a portion oh which that is opposite to the radiation element over the circuit board is made of steel; and a case current suppressor provided in a power supply part of the radiation element to suppress a case current.